Book  (Oct 2001)  Page(s) 153-154.  Includes photo(s).

Book  (Apr 1998)  Page(s) 92.  
 
C. alpina 'Columbine'
... very pale-blue tepals 5 cm (2 in) long
... mid to late spring
... height 2-3 m (6-1/2-10 ft)